The Port Authority of New York and New Jersey expects to take over in October the remaining 93 years of a 99-year lease for Stewart Airport, 55 miles north of New York City. Its Board of Commissioners approved the move to buy the lease from National Express Corp. for $78.5 million on Jan. 25.

A port authority spokesman confirmed the move, which is aimed at creating a fourth New York City-area airport to relieve congestion at LaGuardia, Newark and Kennedy International Airports. With 2,400 acres, two large runways and a passenger terminal, the airport may also help relieve general aviation traffic at New York's Teterboro Airport.

The spokesman would not elaborate on future construction plans at Stewart, which was the nation's first privatized airport when National Express took on the 99-year lease. The next step is to achieve New Jersey approval of legislation extending the port authority's ability to operate facilities more than 25 miles from the Statue of Liberty.